Conventionally, there is known a plug door device that opens/closes a door installed at a doorway of a railroad vehicle or the like. According to one example of the conventional plug door device, when opened/closed, the door is moved in a front-back direction of the vehicle while being moved in a width direction of the vehicle, According to the plug door device thus configured, a seal member attached to a peripheral edge of the door considerably rubs against a wall surface of the doorway and thus becomes worn, so that airtightness of the door is likely to be decreased.
Japanese Examined Patent Application Publication No, Hei 2-27509 (“the '509 Publication”) discloses one example of a technique solving the above-described problem. A plug door device described in the '509 Publication is provided with a first drive source that moves a plug door in a width direction of a vehicle and a second drive source that moves the plug door in an open/close direction that is a front-back direction of the vehicle. In this plug door device, for example, in a case of moving the door from a close position to an open position, the plug door is moved outward in the width direction of the vehicle by the first drive source and then is moved to an open direction by the second drive source. According to the plug door device of the '509 Publication, movement of the door in the width direction is independent of movement of the door in the front-back direction, so that a seal member attached to a peripheral edge of the plug door is unlikely to considerably rub against a wall surface of a doorway. Thus, there can be suppressed a decrease in airtightness of the door due to wearing of the seal member.
The above-described plug door device, however, uses a plurality of drive sources to perform an open/close operation of the door and thus is likely to be increased in size. The present invention has as its object to provide a plug door device that can make a contribution to a size reduction thereof, while suppressing a decrease in airtightness of a door.